💡 This project was built by cape4Labs specifically for the BUIDL BATTLE #2 hackathon.

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🌁 Capebridge

Capebridge is a gateway to swap Base USDC tokens for Stacks USDCX tokens (and vice versa).

It is a decentralized bridge service controlled by a federation of nodes.

The testnet version is already deployed - you can try it here: capebridge.tech.

🌉 How It Works

The protocol works as follows:

• A smart contract is deployed on each supported blockchain, allowing users to deposit their tokens. Once a deposit is made, the tokens are locked and a corresponding bridge event is emitted.

• Federation nodes are listening for these events. Each node independently verifies the deposit and relays the data to the destination chain.

• On the destination blockchain, the smart contract aggregates and compares the submitted data. Once 2 out of 3 nodes reach quorum on a given bridge request, the transfer is approved and a request is executed to release tokens to the user.

• There are no mint or burn mechanics involved, and no wrapped assets are used. Users always receive official Circle tokens — either the widely used USDC on Base or the newly introduced USDCX on Stacks.

🌃 Architecture

Below you can find how the bridge works in both directions step-by-step:

Thus, our project consists of:

(x3) Node:

• Stacks/Base indexer and relayer
• Postgres db
• Stacks signer

(x1) DApp:

• Golang SSE backend
• Nextjs frontend

(x1) Smart Contracts:

• Stacks bridge + federation contract
• Base federation contract
• Base bridge contract

🌌 Production Release

This project is a demonstration of bridging capabilities between Stacks and Base, built specifically for the hackathon. It is not intended to be used as a production-ready solution, and should not be considered a template for deploying real bridges on mainnet.

• Extend admin functionality by adding a broader set of controls for protocol management, monitoring, and emergency actions

• Implement audits both for Clarity and Solidity smart contracts.

• Decentralize node operations by onboarding trusted independent operators.

• Introduce operator fees and define a clear fee model (recommended ~0.4% per transaction).

• Define and enforce minimum and maximum bridge limits to prevent misuse and edge-case risks.

Only after completing all the steps above can the bridge be considered reasonably safe for mainnet deployment and handling user funds.

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